Telephone-exchange system.



E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPTJB, 1905. RENEWED MAR. 19, ms.

Patented Aug. 11,1914

Qnventoz k w WW .Lrcuit M, h; H c-"wires 1 and U 1 r 1 the m'id 3 and. firs 1' coniains the SGPLlWdSUPy relay 6: "wire 12 thg supervisory contra. ml by x @215:

m, bhe su'pernsoz-y relav S",

r the supervism; (JUHMQ'QK relay u :zys S, S joinaly control the local remit of the supervisory lamp 8, While the 59 ,5 rela'vs S and S similarly control the lamp gang relay m 0 n ,(l which it hupp-ms s. The lamp 8, being associated with the air suit is hmher answering plug P, responds to the whim A snhswi rihefs circuit changes, while the lamp using; associated with the c: Hing plug: P 5 5.

I onGs to {h s acts of the called suhscribeiu huh? :lp mlratus and (:i. miks I have I 5.0 110i; claim any 0f their-featmfes as inwmtlon. The invention resides n? $0 33 however, in the parts I am new about to (fie/scribe. For the purpose of 00mn'n'znicnaingz and testing, the operator supposed. tolxme a listening key, as usufl,

1 she has no ringing Key, the relay .u

phme of this key. TheNvin/iin mm connected on one S1619; maxim-aim R through the Wire 1?,

other side fihl'ongh the W a don't Contact n tha rday zzy is connected between the hatter n and the cmd-cbnductor 10 passing to th: sleeve of the calling plug P. It has two mnrmtures s and 8 the first of which Q six; the hwhiery Wire 15 by wires 16 and in'lnfl'hflfi .9 of the relay This n'visoyy relay of the calling phw'. armature 8 of the relay S When ed closes ahranch. 172O from the 1:; to the which is therefore no 1 '& nterconnm also connected to the cord-conductor 10 when the plug 1" is inserted in a jack J.

T he relay R has a pair of armature contacts r, 7, which are normally closed upon back contacts 2 and 1* to maintain the continuity of the cord-conductors 9 and 10. \Vhen the relay is cl'fectively energized, however, the armatures r and r are drawn in to break away from the contacts 1' and r and close upon the contacts '1" and 1*, which form the terminals of a local circuit, including the ringing generator Gr. In other words, the relay acts just as a ringing key would, severing the cord-circuit and connecting the calling plug to the'generator. The sleeve side of the generator circuit is connected through a suitable resistance r to the battery wire 15, in order that while ringing, the cut-elf relay N will be held up without chattering.

The operation of my system thus described is as tollows: Qubscriber A takes down ,his receiver, and lamp on lights. The operator inserts answering-plug P, relays N, S and S become energized, lamp m is extinguished and line wires are connected through the cord to the operators telephone, not shown. Having ascertained the number wanted, the operator tests the jack J with the tip of the plug P, and finding the line idle inserts the plum Relays N and S are a I: Once energized, the line is completed from substation A to the cord-conductors O 10, and the lamp 8 glows. Relay S having completed the circuit from the battery wire 15 through its own windings to the wire 17 and through 20 to the relay R, the commutator R, which is constantly revolving, takes control of the relay, for after each one of its revolutions it grounds the relay through the wire l8, leaving it ungrounded during the other lall revolution. lVhile Ispeak of this a half revolution in each case. it will be understood that it may be anything desired. It the commutator is timed to make one complete revolution in eight seconds, and so divided equally as shown, the relay R would be energized for four seconds and deiinergizcd for four seconds, attracting its armatures, r, 1*, when energized to throw ringing current on the wanted line'and so out to the substation A. Any number of variations can be made in the order and arrangement of the ringing intervals, without departing from my invention. \Vhen the subscriber answers, if the circuit 18 is at the moment broken at the commutator the relay R, will be deiinergized, and when the commutator again closes the circuit it will not become effectively energized by reason of the shunt circuit established around it through the line as Follows: 1 10, I 1, A, 2, J, I (tip), 9, S, ground. The resistance of this line-circuit, from the wire 14 to ground and including the relay S and the talking set at the substation, may vary from about-150 ohms lo J0). Under ordinary conditions, in a well designed system, the maximum will not exceed 350 ohms. I make the \vimlings oi the relay ll high, by preference, 1.000 ohms being a satisfactory resistance. The current supply passing through the 100 ohm relay 8 divides belvrccn thc relays H. and N until the subscribcr answers, and after that the larger part of the current flow passes to line, the proportion passing through the relay It being too small to energize it so as to hold up its armatures. lIcnce the ringing stops.

A number of dili'ercnces may be observed between my system and those heretofore proposed. In some cases a rclay has been cmploycd to connect the ringing generator to line, leaving it so connected until the called subscriber answers, when the consequent rush of current works another relay or magnet to remove the generator from the line. As distinguished from this, it will be perceived that my generator is not directly connected to the line by the act oi" the operator, but that a ringing mechanism is so connected, which is thereafter controlled mechanically by means of the commutator. The generator is in no sense removed from the line by the act of the subscriber. nor is the ringing mechanism disconnected. In fact the latter remains connected throughout the conversation, being merely disabled as long as the linocircuit continues closed. I can, however. provide means for disabling the relay R permanently after the subscriber has answered, this for the purpose of preventing generator current being thrown again upon his line to call him back to the telephone after he has finally hung up the receiver. For this purpose I providea shunt about the relay ll. controlled by the selflocking relay R whose windings are grounded on one side and comuretcd by-wire 21 to a trout contact on the relay S. \Vhen the called subscriber answers the relay S pulls up to extinguish the lamp 8 and at the same time closes the circuit 15, 16, 19, 21 to relay R The relay It then pulls up, locking itself through the short-circuit 1$.)22, and at the same time closing the permancnt shunt 23l-24 about the relay It. -The relay R will continue to hold up even after the subscriber A has opened his line, and the relay R- will therefore continue to be disabled, until plug 1 is pulled.

I have shown only one generator at G, but it will be obvious that the invention may be applied to party-line systems employing any desired arrangement, such for example as shown in Letters Patent No. 779,533 granted to lVilliam Dean January 10, 1905.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

elephone exchange systenn sulfa "ons saving tingeixi, a centml e circuits interconnecting the 1g (1})112115'1'51115 tor the lines antl station ieirn'toir at the cent-ml 'ctions therefore l o em Mae when connection :2 line; e peiioclic circ it completely iing' I relziliv l l'cin loset? it teleplnime eschai' system, the ,mtion with subscrib lines ainl' sigmile, of central of ice connecting nppnrstus, a som-ce oil? sgneling' current, switching means to co. neet said S0111 e to it subline, means intermittently actuating: the swilch' means, 21ml trolled by the St isciiher to piece rein when the subscriber zmsweis.

ing means to connect said. source to a sub cribess line, a commutator controlling said switching means at intervals, and means controlled by the subscriber to close his line so as to form a relatively low resistance shunt about the switching means to disable the same between intervals.

In testimony whereof I have allixed niy signature in presence of two witnesses.

EDWARD E. CLEMENT. Witnesses l Enmons'ron, J11, JAMES Meme 

